Dr Fox, who set up the MPRB in June, said: "It is clear that the additional rigour and scrutiny being applied through the Major Projects Review Board is having a beneficial effect on the behaviours of our suppliers."

"I am pleased that both Falcon and Watchkeeper have made progress since the board's first meeting. However, I am not satisfied with the progress of the Valiant Jetty Project. It is almost four years late and over budget.

"We must learn from the mistakes of the past and move away from the culture of optimism. Too frequently projects ran over-budget and overtime, without any meaningful remedial action.

"Real budgetary discipline can only be achieved through the effective real-time control of project budgets. Our Armed Forces and our country simply cannot afford anything less."

The Valiant Jetty is to serve the new Astute class submarine at the Royal Navy's Clyde base.

It is to deliver base porting facilities for the UK submarine fleet for the next 50 years.

According to its contract, the project should have completed in October 2008.

Amec's earliest estimate of completion is now nearly four years after that, and its latest cost estimate is almost 70% more than the contractual maximum price of £134 million, defence officials said